Obama faces new political fire for Saturday's developments in Iran. (Chris McGrath/Getty Images)

President Barack Obama's legacy became further tied to Tehran on Saturday when Iran released four American prisoners and U.N. inspectors cleared the way for the easing of some painful sanctions on the Middle Eastern power.

Obama is taking new political fire from Republican presidential hopefuls and lawmakers -- joined by some notable Democrats -- over the nuclear deal his administration and other world powers inked with Iran that made the sanctions lifting possible. Now, he is under new attacks after swapping seven Iranians for Washington Post reporter Jason Rezaian and three other Americans.

The lawmakers, including Sens. Ted Cruz, R-Texas, and John McCain, R-Ariz., on Monday filed an amicus brief in Wisconsin federal court, supporting Johnson’s challenge to the Office of Personnel Management rule on the issue. In response to a March 17 Justice Department request to dismiss the lawsuit, the GOP members argue that Johnson's case deserves to be heard.